Magnetostrictive material and magnetostriction type device using the same

ABSTRACT

A magnetostrictive material includes a FeGaSm alloy that is represented by Expression (1), 
       Fe (100-x-y) Ga x Sm y   (1)
         (in Expression (1), x and y are respectively a content rate (at. %) of Ga and a content rate (at. %) of Sm, and satisfy that y≤0.35x−4.2, y≤−x+20.1, and y≥−0.1x+2.1).

TECHNICAL FIELD

The technical field relates to a magnetostrictive material which isformed of a FeGaSm alloy, and a magnetostriction type device using thesame.

BACKGROUND

In recent years, it is expected that the world in which things havingautonomous communication functions perform information interchanges, andautomatically perform mutual controls, that is, the world of Internet ofthings (IoT) arrives. If the IoT infiltrates into a society, IoT deviceshaving the communication functions will appear on the market in largequantities. There will be a need for a power source in order to operatethe IoT device such as a sensor. However, if the number of devicesbecomes enormous, it is difficult to secure the power source in terms ofwiring, maintenance time, and cost. Therefore, a power supply technologywhich is suitable for the IoT device is demanded in realization of theIoT. Based on such a background, “energy harvesting” which is atechnology of utilizing micro energy that is present everywhere in oursurroundings by converting the micro energy into power is beingconsidered. Since a vibration which is one of energy sources isnecessarily generated whenever an automobile, a railroad, a machine, ora person moves, the vibration is an energy source of which manygeneration spots are present, and which is not affected by weather andclimate. Therefore, it is considered that construction of a system inwhich the power supply of an application coupled with the movement ofthe moving bodies is provided by vibration power generation may be aclue to the realization of the IoT.

Power generation methods of the vibration power generation areclassified into four kinds: a magnetostriction type; a piezoelectrictype; an electrostatic induction type; and an electromagnetic inductiontype. The magnetostriction type is a method for converting a magneticflux which leaks to an outside in accordance with a change of aninternal magnetic field of a magnetostrictive material by applyingstress into electricity through a wound coil. Since internal resistanceof the magnetostriction type is smaller than those of other methods, apower generation quantity is large. Since a metal alloy is used as amagnetostrictive material, the magnetostriction type has a feature ofbeing excellent in durability. Therefore, the magnetostriction type maybe expected as a method that is capable of improving the durabilitywhich is one of problems of the vibration power generation device.

On the other hand, as a magnetostrictive material of the vibration powergeneration device, a material of FeGa (galfenol)-based alloy isdeveloped. Since the FeGa-based alloy does not include a rare earthelement in the material thereof, and has a large magnetostrictionquantity, the FeGa-based alloy is expected to be used as a sensor or anactuator. For example, Japanese Patent Unexamined Publication No.2008-69434 discloses a magnetostrictive material of a FeGaAl-based alloywhich is used in a magnetostriction type torque sensor for a vehicle.

Specifically, the magnetostriction type torque sensor using an alloywhich includes B of 1 to 2 at. %, Al of 4 to 7 at. %, Ga of 12 to 14 at.%, and a balance of Fe is described in Japanese Patent UnexaminedPublication No. 2008-69434. Regarding the FeGaAl-based alloy, anadditional element, an addition quantity thereof, a structure, a heattreatment, and the like are appropriately controlled, thereby, it ispossible to improve mechanical strength of the magnetostrictive materialwhich is formed of the alloy.

SUMMARY

However, in the current magnetostriction type vibration power generationdevice, power generation density (power generation quantity per volume)is small, and it is not possible to realize miniaturization which mayachieve the realization of the IoT. For a practical use, there is a needto improve the power generation density of the device, by improving themagnetostriction quantity of the magnetostrictive material that is in arelationship which is proportional to the power generation density. Forexample, in a case where the magnetostriction type vibration powergeneration device is applied to a tire pressure monitoring system or asensor network in a factory, power consumption density of approximately0.3 mW/cm³ is obtained, and there is a need to be 400 ppm or greater asa magnetostriction quantity. The magnetostrictive material described inJapanese Patent Unexamined Publication No. 2008-69434 is excellent inmechanical strength, but has small magnetostriction quantity ofapproximately 50 ppm, thereby, it is not possible to realize theminiaturization as a vibration power generation device.

An object of the present disclosure is to provide a magnetostrictivematerial which exhibits a large magnetostriction quantity, and isexcellent in mechanical strength.

According to an aspect of the present disclosure, there is provided amagnetostrictive material including a FeGaSm alloy that is representedby Expression (1),

Fe_((100-x-y))Ga_(x)Sm_(y)  (1)

(in Expression (1), x and y are respectively a content rate (at. %) ofGa and a content rate (at. %) of Sm, and satisfy that y≤0.35x−4.2,y≤−x+20.1, and y≥−0.1x+2.1).

In the aspect of the present disclosure, in Expression (1), x and y maysatisfy that 17≤x≤18 and 0.7≤y≤1.4.

In the aspect of the present disclosure, an orientation difference of<100> orientation of the FeGaSm alloy may be in a range of 0° or greaterand 10° or less, with respect to a maximum strain direction of themagnetostrictive material.

According to another aspect of the present disclosure, there is provideda magnetostriction type device including the magnetostrictive materialdescribed above, in which a maximum strain direction of themagnetostrictive material is configured to form an inclination angle of0° or greater and 10° or less, with respect to a predetermined directionof a dimensional change of the magnetostriction type device.

According to the present disclosure, a magnetostrictive material whichexhibits a large magnetostriction quantity, and is excellent inmechanical strength is provided.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a schematic diagram when one example in which a maximum straindirection of a magnetostrictive material is configured to form aninclination angle of 0°, with respect to a predetermined direction of adimensional change of a magnetostriction type device according to anembodiment is viewed from above.

FIG. 2 is a schematic diagram when one example in which the maximumstrain direction of the magnetostrictive material is configured to formthe inclination angle of θ, with respect to the predetermined directionof the dimensional change of the magnetostriction type device accordingto the embodiment is viewed from above.

FIG. 3 is a diagram representing a relationship between a content rateof Ga and a content rate of Sm in which a magnetostriction quantitybecomes 400 ppm or greater in Example 2 of the present disclosure.

FIG. 4 is a diagram representing the relationship between the contentrate of Ga and the content rate of Sm in which the magnetostrictionquantity becomes 480 ppm or greater in Example 2 of the presentdisclosure.

DESCRIPTION OF EMBODIMENTS

Hereinafter, a magnetostrictive material, a method for manufacturing thesame, and a magnetostriction type device according to an embodiment ofthe present disclosure will be described, but the present disclosure isnot limited to such an embodiment.

Magnetostrictive Material and Magnetostriction Type Device

The magnetostrictive material according to the present embodimentincludes a FeGaSm alloy that is represented by Expression (1),

Fe_((100-x-y))Ga_(x)Sm_(y)  (1)

(in Expression (1), x and y are respectively a content rate (at. %) ofGa and a content rate (at. %) of Sm, and satisfy that y≤0.35x−4.2,y≤−x+20.1, and y≥−0.1x+2.1).

In the present disclosure, a material in which a dimensional change maybe generated by applying a magnetic field is referred to as a“magnetostrictive material”. The magnetostrictive material of thepresent embodiment may have any suitable form or shape so long as themagnetostrictive material is formed of the FeGaSm alloy described above.The magnetostrictive material may have any suitable shape, may have abulk shape (or a massive shape), for example, a cylindrical shape, acubic shape, a rectangular parallelepiped shape, or otherthree-dimensional shapes, or may be a sheet (thin film shape, thin bandshape, or the like) that may have a sheet shape, for example, a circularshape, an elliptical shape, a rectangular shape, or other planar shapes(or surfaces).

In the present disclosure, the “content rate” of an element is aproportion of the number of atoms of each element to the number of atomsof the whole FeGaSm alloy, and is represented using a unit of at. %(atomic percent). In more detail, the FeGaSm alloy is analyzed with anelectron probe micro analyzer (EPMA), thereby, it is possible to measurethe content rate of each element.

In the magnetostrictive material of the present embodiment, compositionof the FeGaSm alloy may include a trace element (for example, oxygenthat is less than 0.005 at. %) which is inevitably mixed so long asbeing substantially configured by the exemplified element.

In the magnetostrictive material according to the present embodiment, itis possible to realize high magnetostriction quantification, due to aninfluence on local strain that is caused by adding Sm of which an atomicradium is larger than that of Fe or Ga to the composition of a FeGaalloy, and magneto crystalline anisotropy that is caused by quadrupolemoment of a 4f electron which the added Sm has. The content rate of Smin the FeGaSm alloy is in a range (y≤0.35x−4.2, y≤−x+20.1, andy≥−0.1x+2.1, see FIG. 3 described later) that is represented by theexpression described above, thereby, for the reason of the influence onthe local strain and the magneto crystalline anisotropy, it is possibleto realize improvement of the magnetostriction quantity, and it ispossible to maintain mechanical strength, in comparison with aFeGaAl-based alloy of the related art as described in Japanese PatentUnexamined Publication No. 2008-69434.

A proportion of the dimensional change due to a magnetostriction effectin the magnetostrictive material is referred to as a magnetostrictionquantity. In more detail, in the present disclosure, themagnetostriction quantity (ppm) is represented by a value obtained bysubtracting strain that is measured when the magnetic field is appliedperpendicularly to a gauge axis of a strain gauge, from the strain of asample when the magnetic field is applied parallel to the gauge axis ofthe strain gauge.

In the magnetostrictive material according to the present embodiment, inExpression (1), x and y satisfy that 17≤x≤18, and 0.7≤y≤1.4 (see FIG. 4described later), thereby, it is possible to realize the highmagnetostriction quantification more effectively.

In the present embodiment, the FeGaSm alloy may have any crystalstructure, and may have, for example, a monocrystalline structure or apolycrystalline structure.

In the present embodiment, for example, it is possible to make anorientation difference of <100> orientation of the FeGaSm alloy be inthe range of 0° or greater and 10° or less, with respect to a maximumstrain direction of the magnetostrictive material. Such an orientationdifference is preferably 0° or greater and 8° or less, more preferably0° or greater and 6° or less, and further preferably 0° or greater and4° or less.

By making the magnetostrictive material be in a crystal state in thismanner, it is possible to favorably and easily obtain magnetostrictiveproperties more efficiently, and the magnetostrictive material may bemore appropriately used when being used in the magnetostriction typedevice described later. This is considered that the present disclosureis not bound by any theory, but the <100> orientation is an orientationwhich is likely to be magnetized in the FeGaSm alloy, and themagnetostrictive properties are obtained more efficiently, by making theorientation difference of the <100> orientation of the FeGaSm alloy withrespect to the maximum strain direction of the magnetostrictive materialbe in the range of 10° or less as small as possible (for example, thelarger magnetostriction quantity is obtained by applying the samemagnetic field, or the same magnetostriction quantity is obtained byapplying the smaller magnetic field, in comparison with a case where theorientation difference described above exceeds 10°).

In the present disclosure, the “maximum strain direction of themagnetostrictive material” means a direction in which the strain(dimensional change proportion) of the magnetostrictive material becomesthe maximum in a case where the magnetic field is applied to themagnetostrictive material that may have any shape (in a case where thecrystal structure of the magnetostrictive material is not clear, forexample, the “maximum strain direction of the magnetostrictive material”is capable of being determined in trial and error manner, by measuringthe strain in any direction of the magnetostrictive material whileappropriately adjusting an applying direction of the magnetic field). Inthe present disclosure, the orientation difference of the <100>orientation of the FeGaSm alloy may be determined by a known method,with respect to the maximum strain direction of the magnetostrictivematerial, and may be determined by, for example, an electron backscatterdiffraction (EBSD) method. In more detail, it is possible to determinesuch an orientation difference, by applying a crystal orientation mapdue to the EBSD method to the surface of the FeGaSm alloy of themagnetostrictive material according to the present embodiment, andmeasuring a distribution condition of the <100> orientation with respectto the maximum strain direction (this is understood as a sampledirection, or a specified direction in a sample coordinate system) ofthe magnetostrictive material (the surface may be a surface which themagnetostrictive material originally has, or may be a surface which isexposed when the crystal orientation map is applied, and may be selectedin accordance with the maximum strain direction of the magnetostrictivematerial). Specifically, for example, “the orientation difference of the<100> orientation of the FeGaSm alloy is in the range of 0° or greaterand 10° or less, with respect to the maximum strain direction of themagnetostrictive material” means that at the time of this measurement,in a case where a measuring point in which the <100> orientation withrespect to the maximum strain direction of the magnetostrictive materialis oriented to be 0° or greater and 10° or less is sought, theproportion of such measuring points to the measuring points in ameasurable area is 100%, that is, in all measuring points of themeasurable area, the <100> orientation with respect to the maximumstrain direction of the magnetostrictive material is oriented to be 0°or greater and 10° or less. Other numerical value ranges relating to theorientation difference may be understood in the same manner.

In the present embodiment, the magnetostriction type device includingthe magnetostrictive material as described above is also provided. Inthe present disclosure, the “magnetostriction type device” indicates adevice that includes the magnetostrictive material described above, inmore detail, includes the magnetostrictive material as a configurationelement (for example, a magnetostriction element), and has a structurewhich may extract energy (for example, power generation energy) usingthe same. Specifically, for example, various kinds of magnetostrictiontype apparatuses such as a magnetostriction type vibration powergeneration device, a magnetostriction type sensor, and amagnetostriction type actuator are cited. In the devices, themagnetostrictive material is included as a portion thereof in astructure and/or a shape suitable for each apparatus.

In the magnetostriction type device according to the present embodiment,the maximum strain direction of the magnetostrictive material may beconfigured to form an inclination angle of 0° or greater and 10° orless, with respect to a predetermined direction of the dimensionalchange of the magnetostriction type device. The inclination angle ismore preferably 0° or greater and 8° or less, further preferably 0° orgreater and 6° or less, and more further preferably 0° or greater and 4°or less.

The magnetostriction type device is configured with such an inclinationangle, thereby, it is possible to obtain the magnetostrictive propertiesmore efficiently. This is because it is possible to use themagnetostrictive properties of the magnetostrictive material moreefficiently, by making the inclination angle between the maximum straindirection of the magnetostrictive material and the predetermineddirection of the dimensional change of the magnetostriction type devicebe in the range of 10° or less as small as possible (for example, it ispossible to use the larger magnetostriction quantity for the device byapplying the same magnetic field, or it is possible to use the samemagnetostriction quantity for the device by applying the smallermagnetic field, in comparison with a case where the inclination angledescribed above exceeds 10°).

In the present disclosure, the predetermined direction of thedimensional change of the magnetostriction type device is a direction inwhich the dimensional change of the magnetostrictive material ispredetermined or desired in the magnetostriction type device, forexample, in order to extract the energy from the magnetostriction typedevice, and is a direction that may be determined in accordance with theapplying direction of the magnetic field to the magnetostrictivematerial in the magnetostriction type device, and the shape, thestructure and/or a use purpose of the magnetostriction type device. Inthe present disclosure, the inclination angle of the maximum straindirection of the magnetostrictive material is determined in a statewhere the magnetostrictive material is incorporated into themagnetostriction type device, with respect to the predetermineddirection of the dimensional change of the magnetostriction type device.

A specific example of the magnetostriction type device will be describedwith reference to drawings. FIG. 1 is a schematic diagram when oneexample in which the maximum strain direction of the magnetostrictivematerial is configured to form the inclination angle of 0°, with respectto the predetermined direction of the dimensional change of themagnetostriction type device according to the embodiment is viewed fromabove. As illustrated in FIG. 1, in magnetostriction type device 1,maximum strain direction β1 of magnetostrictive material 2 which isdetermined by the method described before becomes parallel, that is,forms the inclination angle of 0°, with respect to predetermineddirection α1 of the dimensional change thereof. FIG. 2 is a schematicdiagram when one example in which the maximum strain direction of themagnetostrictive material is configured to form the inclination angle ofθ, with respect to the predetermined direction of the dimensional changeof the magnetostriction type device according to the embodiment isviewed from above. As illustrated in FIG. 2, in magnetostriction typedevice 2, maximum strain direction β2 of magnetostrictive material 4which is determined by the method described before forms the inclinationangle of θ, with respect to predetermined direction α2 of thedimensional change thereof. In this case, θ may form the inclinationangle of 0° or greater and 10° or less, as described before. Aconfiguration with such an inclination angle may be made, thereby, it ispossible to obtain the magnetostrictive properties by themagnetostrictive material more efficiently.

Method for Manufacturing Magnetostrictive Material

It is possible to use any suitable alloy manufacturing method so long asa method for manufacturing the magnetostrictive material according tothe present embodiment is a method for obtaining the magnetostrictivematerial of the FeGaSm alloy, and the method for manufacturing themagnetostrictive material according to the present embodiment is notparticularly limited. For example, Czochralski method (CZ method),Bridgman method, a rapid solidification method, or the like is cited. Ifthe manufacturing is performed by the CZ method, it is possible toaccurately manufacture chemical composition and crystal orientation, ina large-sized crystal.

EXAMPLES

Hereinafter, the present disclosure will be described in more detail byExamples and Comparative Examples, but the present disclosure is notlimited to Examples.

Example 1

In Example 1, a sample of a FeGaSm alloy in which Sm is added to a FeGaalloy is manufactured, measurements in mechanical strength andmagnetostriction quantity are performed, and effectiveness of additionof Sm is confirmed.

Manufacturing of Sample for Measurement of FeGaSm Alloy

As illustrated in Table 1 later, a plurality of samples (Example 1-1 toExample 1-3, and Comparative Example 1-1 to Comparative Example 1-3) ofthe FeGaSm alloys which are configured by the content rate (at. %) ofGa, the content rate (at. %) of Sm, and the content rate (at. %) of abalance Fe are prepared.

In order to manufacture each alloy sample, first, Fe (purity of99.999%), Ga (purity of 99.999%), and Sm (purity of 99.99%) arerespectively weighed using an electronic balance. The content rate ofeach element in each alloy sample is measured and adjusted by an EPMAanalysis.

Each alloy sample is grown using a high-frequency induction heating typeCZ furnace. A crucible of an outer diameter of ϕ45 mm which is made ofdense alumina is disposed on an inside of a graphite crucible of aninner diameter of ϕ50 mm, and 400 g of a raw material of Fe, Ga, and Smis put into each weighed alloy sample. After the crucible into which theraw material is put is put into a growth furnace, and vacuum is made inthe furnace, an argon gas is introduced thereto. Thereafter, the heatingof the apparatus is started, in a time point at which the inside of thefurnace reaches atmospheric pressure, and the heating is performed for12 hours, until a melting liquid is made. FeGa single crystal which iscut out in the <100> orientation is used as a seed crystal, and the seedcrystal descends close up to the melting liquid. The seed crystalgradually descends while rotating at 5 ppm, and a tip of the seedcrystal is in contact with the melting liquid. While a temperature isgradually decreased, thereafter, the seed crystal is increased at aspeed of which a pulling-up speed is 1.0 mm/hr, and a crystal growth isperformed. As a result, a single crystal alloy of which a diameter is 10mm, and a length of a straight body is 80 mm is obtained. The obtainedsingle crystal alloy is cut out into each sample shape for themeasurement described hereinafter, by wire electric discharge machining.

Measurement of Mechanical Strength (Tensile Strength (MPa) andElongation (%))

The measurement of the mechanical strength is performed under a roomtemperature environment (25° C.) using a tensile tester. The sample forthe measurement is a specimen of a dumbbell shape, and a fixer thereofis set to be the diameter of 6 mm×the length of 20 mm, and a neckthereof is set to be the diameter of 3 mm×the length of 20 mm. Adistance between gripers of the tester is set to 20 mm, and load isapplied in an axis direction until the specimen is broken, after thespecimen is fixed. Elongation (%) is a proportion of an increment of thedistance between the grippers at the time of the breakage to 20 mm ofthe distance between the grippers before the test. For example, in acase where the distance between the grippers at the time of breaking thespecimen is 40 mm, the elongation is that (40−20)/20×100=100(%).

Measurement of Magnetostriction Quantity (ppm)

The measurement of the magnetostriction quantity is performed under theroom temperature environment (25° C.), by a strain gauge method which isgenerally used. A vibrating material type magnetometer is used in amagnetic field generation apparatus. The strength of the magnetic fieldis 5000 Oe. As a sample for the measurement, a sample obtained bycutting out the single crystal alloy (the diameter of 10 mm×the lengthof the straight body of 80 mm) described above into the shape of thediameter of 10 mm×a thickness of 1 mm is used. At this time, the <100>orientation which is an easy axis of magnetization of the crystal is cutout to be a thickness direction of the sample. That is, an upper surfacedirection and a bottom surface directions of the sample of which thediameter is 10 mm, and the thickness direction of 1 mm are made 0°, withrespect to the <100> orientation of the FeGaSm alloy. The strain gaugeis attached to the upper surface of the sample of which the diameter is10 mm. At this time, the strain gauge is attached to be parallel to the<100> orientation of the FeGaSm alloy. In other words, the properties ofthe magnetostriction quantity of the sample are measured to be parallelto the maximum strain direction (to form the inclination angle of 0°),with respect to the pulling-out direction of magnetostrictive energy.The strain (λ_(//)) of the sample when the magnetic field is appliedparallel to the gauge axis of the strain gauge, and the strain (λ_(⊥))of the sample when the magnetic field is applied perpendicularly to thegauge axis of the strain gauge are recorded with a data logger.Magnetostriction quantity λ (ppm) is calculated as λ (ppm)=λ_(//)−λ_(⊥),and is evaluated, from the recorded numerical values.

Table 1 illustrates measurement results of the mechanical strength(tensile strength and elongation) and the magnetostriction quantity, inconjunction with the alloy composition of each sample of the FeGaSmalloy in Example 1-1 to Example 1-3, and Comparative Example 1-1 toComparative Example 1-3.

TABLE 1 Magneto- Tensile Elon- striction Fe Ga Sm Strength gationQuantity [at. %] [at. %] [at. %] [MPa] [%] [ppm] Example 1-1 83.3 16 0.7353 1 432 Example 1-2 83 16 1 364 1.1 461 Example 1-3 82.6 16 1.4 351 1420 Comparative 83.3 16.7 0 342 1 298 Example 1-1 Comparative 83 17 0351 1.1 307 Example 1-2 Comparative 82.6 17.4 0 350 1.1 295 Example 1-3

As illustrated in Table 1, in Example 1-1 to Example 1-3 in which Sm isadded to the FeGa alloy, the magnetostriction quantity is 400 ppm orgreater, while the same mechanical strength is maintained (the tensilestrength is approximately 350 MPa, and the elongation is approximately10), in comparison with Comparative Example 1-1 to Comparative Example1-3 in which Sm is not added. This is considered that themagnetostriction quantity is improved due to the influence on the localstrain that is caused by the addition of Sm, and the magneto crystallineanisotropy that is caused by the quadrupole moment of the 4f electron.Accordingly, it is found out that the addition of Sm is effective inorder to improve the magnetostriction quantity while maintaining themechanical strength.

Example 2

In Example 2, various samples in which the content rate (at. %) of Sm ischanged in the FeGaSm alloy are prepared, the magnetostriction quantityis measured, and the range of the content rate (at. %) of Sm in whichthe addition of Sm becomes effective is clarified.

Manufacturing of Sample for Measurement of FeGaSm Alloy

As a sample for the measurement, as illustrated in Table 2 later, theplurality of samples (Example 2-1 to Example 2-15, and ComparativeExample 2-1 to Comparative Example 2-9) of the FeGaSm alloys which areconfigured by the content rate (at. %) of Ga, the content rate (at. %)of Sm, and the balance Fe (the numerical value thereof is notillustrated in Table 2) are prepared. The method for manufacturing thesample for the measurement of the FeGaSm single crystal alloy, and themethod (wire electric discharge machining) for cutting out the samplefor the measurement are the same as those of Example 1 described above.

Measurement and Determination of Magnetostriction Quantity (Ppm)

The shape of the sample for the measurement of the magnetostrictionquantity (ppm) of each sample, and a measurement method thereof are thesame as those of Example 1 described above. In a case where themagnetostrictive material is used for the vibration power generationdevice, if the magnetostriction quantity is less than 400 ppm, powergeneration density is less than 0.3 mW/cm³. Therefore, the effectivenessof the magnetostriction quantity (ppm) is determined to be “Good” in acase of 400 ppm or greater, and is determined to be “Poor” in a case ofless than 400 ppm. In a case where the magnetostrictive material is usedfor a torque sensor, if the magnetostriction quantity is 480 ppm orgreater, output sensitivity of 1 V/Nm or greater is obtained, and it ispossible to use the torque sensor of the magnetostriction material in anelectric assist bicycle or the like. Therefore, the sample of which themagnetostriction quantity is 480 ppm or greater is determined to be“Excellent”.

Table 2 illustrates the measurement result and a determination result ofthe magnetostriction quantity, in conjunction with the alloy compositionof each sample of the FeGaSm alloy in Example 2-1 to Example 2-15, andComparative Example 2-1 to Comparative Example 2-9.

TABLE 2 Ga Sm Magnetostriction [at. %] [at. %] Quantity [ppm]Determination Example 2-1 20 0.1 415 Good Example 2-2 17 0.4 433 GoodExample 2-3 19.7 0.4 417 Good Example 2-4 14 0.7 419 Good Example 2-5 160.7 432 Good Example 2-6 17 0.7 491 Excellent Example 2-7 18 0.7 483Excellent Example 2-8 19.4 0.7 421 Good Example 2-9 16 1 461 GoodExample 2-10 17.5 1 516 Excellent Example 2-11 16 1.4 420 Good Example2-12 17 1.4 484 Excellent Example 2-13 18 1.4 487 Excellent Example 2-1418.7 1.4 425 Good Example 2-15 18 2.1 421 Good Comparative 19 0.1 389Poor Example 2-1 Comparative 20.7 0.1 375 Poor Example 2-2 Comparative16 0.4 392 Poor Example 2-3 Comparative 13 0.7 377 Poor Example 2-4Comparative 20.1 0.7 381 Poor Example 2-5 Comparative 15.3 1.4 390 PoorExample 2-6 Comparative 19.4 1.4 393 Poor Example 2-7 Comparative 17 2.1390 Poor Example 2-8 Comparative 18.7 2.1 388 Poor Example 2-9

As illustrated in Table 2, the magnetostriction quantities of Example2-1 to Example 2-15 are 400 ppm or greater, and all the determinationsthereof are “Excellent” or “Good”. This is considered to be due to theinfluence on the local strain that is caused by the addition of Sm, andthe magneto crystalline anisotropy that is caused by the quadrupolemoment of the 4f electron.

In a case where the content rate of Ga is 19 at. %, and the content rateof Sm is 0.1 at. % in Comparative Example 2-1, in a case where thecontent rate of Ga is 16 at. %, and the content rate of Sm is 0.4 at. %in Comparative Example 2-3, and in a case where the content rate of Gais 13 at. %, and the content rate of Sm is 0.7 at. % in ComparativeExample 2-4, the magnetostriction quantity is less than 400 ppm, and thedetermination becomes “Poor”. This is considered because it is notpossible to express the sufficient magnetostriction quantity improvementeffect, since the content rate of Sm is small.

In a case where the content rate of Ga is 20.7 at. %, and the contentrate of Sm is 0.1 at. % in Comparative Example 2-2, in a case where thecontent rate of Ga is 20.1 at. %, and the content rate of Sm is 0.7 at.% in Comparative Example 2-5, in a case where the content rate of Ga is19.4 at. %, and the content rate of Sm is 1.4 at. % in ComparativeExample 2-7, and in a case where the content rate of Ga is 18.7 at. %,and the content rate of Sm is 2.1 at. % in Comparative Example 2-9, themagnetostriction quantity is less than 400 ppm, and the determinationbecomes “Poor”. This is considered that the total content rate of Ga andSm is as high as 20.8 at. %, and the crystal structure is changed to anordered phase (D03, L12) from a disorder bcc phase, thereby, themagnetostriction quantity is lowered.

In a case where the content rate of Ga is 15.3 at. %, and the contentrate of Sm is 1.4 at. % in Comparative Example 2-6, and in a case wherethe content rate of Ga is 17 at. %, and the content rate of Sm is 2.1at. % in Comparative Example 2-8, the magnetostriction quantity is lessthan 400 ppm, and the determination becomes “Poor”. This is consideredthat the magnetostriction quantity is lowered by of appearance of thesecond phase, since Sm is added beyond a solid solubility limit.

For example, if Example 2-2 or Example 2-3 is compared with ComparativeExample 2-3, or Example 2-11 to Example 2-14 are compared withComparative Example 2-6, even in a case of the same content rate of Sm,the content rate of Ga is low, and the magnetostriction quantity is lessthan 400 ppm. This is considered to be caused by the fact that themagnetostriction quantity is lowered as the content rate of Ga islowered, in a FeGa-based alloy (of which the content rate of Ga is 20at. % or less).

FIG. 3 is a diagram representing a relationship between the content rateof Ga and the content rate of Sm in which the magnetostriction quantitybecomes 400 ppm or greater in Example 2 of the present disclosure. Avertical axis indicates the content rate (at. %) of Sm, and a horizontalaxis indicates the content rate (at. %) of Ga. A black circle representsa spot at which the magnetostriction quantity is 400 ppm or greater inExample 2-1 to Example 2-15. A white circle represents a spot at whichthe magnetostriction quantity is less than 400 ppm in ComparativeExample 2-1 to Comparative Example 2-9. As illustrated in FIG. 3, aboundary at which the magnetostriction quantity is 400 ppm or greater ispresent, in the relationship between the content rate of Sm and thecontent rate of Ga. If approximate lines along the boundary are sought,it is found out that y=0.35x−4.2, y=−x+20.1, and y=−0.1x+2.1,respectively. In other words, if the content rate of Sm and the contentrate of Ga are present on the inside of an area including a borderlinethat is surrounded by the approximate lines illustrated by oblique linesin FIG. 3, the magnetostriction quantity becomes 400 ppm or greater.That is, if the magnetostrictive material is the FeGaSm alloy that isrepresented by Expression (1): Fe_((100-x-y))Ga_(x)Sm_(y) . . . (1) (inExpression (1), x and y are respectively the content rate (at. %) of Ga,and the content rate (at. %) of Sm, and satisfy that y≤0.35x−4.2,y≤−x+20.1, and y≥−0.1x+2.1), the magnetostriction quantity becomes 400ppm or greater.

FIG. 4 is a diagram representing the relationship between the contentrate of Ga and the content rate of Sm in which the magnetostrictionquantity becomes 480 ppm or greater in Example 2 of the presentdisclosure. Specifically, FIG. 4 is a diagram in which a spot at whichthe magnetostriction quantity is 480 ppm or greater is particularlyrepresented by a double circle, among the black circles at which themagnetostriction quantities are 400 ppm or greater. As illustrated inFIG. 4, the boundary at which the magnetostriction quantity is 480 ppmor greater is present, in the relationship between the content rate ofSm and the content rate of Ga. If the approximate lines along theboundary are sought, it is found out that x=17, x=18, y=0.7, and y=1.4,respectively. In other words, if the content rate of Sm and the contentrate of Ga are present on the inside of the area including a dashedborderline that is surrounded by the approximate lines in the obliquelines of FIG. 4, the magnetostriction quantity becomes 480 ppm orgreater. That is, if the magnetostrictive material is the FeGaSm alloythat is represented by Expression (1): Fe_((100-x-y))Ga_(x)Sm_(y) . . .(1) (in Expression (1), x and y satisfy that 17≤x≤18, and 0.7≤y≤1.4),the magnetostriction quantity becomes 480 ppm or greater.

Example 3

In Example 3, various samples in which the inclination angle withrespect to the <100> orientation is changed, at the time of cutting outthe sample for the measurement of the FeGaSm single crystal alloy areprepared, the magnetostriction quantity is measured, and an influencewhich the inclination angle with respect to the <100> orientation of thealloy has on the magnetostriction quantity is searched.

Manufacturing of Sample for Measurement of FeGaSm Alloy

As a sample for the measurement, as illustrated in Table 3 later,samples (Example 3-1 to Example 3-6, and Comparative Example 3-1 toComparative Example 3-2) of the FeGaSm alloys which are configured bythe content rate of Ga which is 20 at. %, the content rate of Sm whichis 0.1 at. %, and the balance Fe are prepared. The method formanufacturing the sample for the measurement of the FeGaSm singlecrystal alloy, and the method (wire electric discharge machining) forcutting out the sample for the measurement are the same as those ofExample 1 described above.

Measurement and Determination of Magnetostriction Quantity (ppm)

The shape of the sample for the measurement of the magnetostrictionquantity (ppm) of each sample is a shape of the diameter of 10 mm×thethickness of 1 mm, and is the same as that of Example 1. However, persample, the upper surface and the bottom surface (surface that isparallel to a surface which is orthogonal to the thickness direction ofthe sample) of the sample of which the diameter is 10 mm are cut out toform the different inclination angles as illustrated in Table 3, withrespect to the <100> orientation of the single crystal of the FeGaSmalloy. The measurement method of the magnetostriction quantity (ppm) ofeach sample is the same as the method of Example 1 described above, buteven in a case of the sample according to Example 3 which is cut outwith the inclination angle, the strain gauge is attached to the uppersurface of the sample of which the diameter is 10 mm, in the samemanner. Accordingly, the properties of the magnetostriction quantity ofthe sample are measured such that the maximum strain direction of themagnetostrictive material forms the inclination angle which is the sameas that of Table 3, with respect to the pulling-out direction of themagnetostrictive energy. The effectiveness of the magnetostrictionquantity (ppm) is determined to be “Good” in a case of 400 ppm orgreater, and is determined to be “Poor” in a case of less than 400 ppm.

Table 3 illustrates the measurement result and the determination resultof the magnetostriction quantity, in conjunction with the alloycomposition and the inclination angle of each sample of the FeGaSm alloyin Example 3-1 to Example 3-6, and Comparative Example 3-1 toComparative Example 3-2.

TABLE 3 Magneto- Ga Sm Inclination striction Deter- [at. %] [at. %]Angle [°] Quantity [ppm] mination Example 3-1 20 0.1 0 415 Good Example3-2 20 0.1 2 416 Good Example 3-3 20 0.1 4 410 Good Example 3-4 20 0.1 6409 Good Example 3-5 20 0.1 8 405 Good Example 3-6 20 0.1 10 401 GoodComparative 20 0.1 11 396 Poor Example 3-1 Comparative 20 0.1 12 393Poor Example 3-2

As illustrated in Table 3, in a case where the content rate of Ga is 20at. %, and the content rate of Sm is 0.1 at. %, in Example 3-1 toExample 3-6 of which the inclination angle is 0° or greater and 10° orless, the magnetostriction quantity is 400 ppm or greater, and thefavorable result is obtained, in comparison with Comparative Example 3-1to Comparative Example 3-2 having the same alloy composition. This isconsidered because the easy axis of magnetization of the FeGaSm alloy isthe <100> orientation. Accordingly, practically, for example, it isfound out to be more useful that the direction in which the dimensionalchange for extracting the energy of the magnetostriction type device isdesired, and the maximum strain direction of the magnetostrictivematerial are configured to form the inclination angle of 0° or greaterand 10° or less, in order to obtain the magnetostrictive properties moreefficiently.

Since the magnetostrictive material of the present disclosure exhibitslarge magnetostriction quantity, and is excellent in mechanicalstrength, it is possible to apply the magnetostrictive material of thepresent disclosure to a magnetostriction type vibration power generationdevice, a magnetostriction type sensor, or a magnetostriction typeactuator, thereby assisting in the realization of the IoT.

What is claimed is:
 1. A magnetostrictive material comprising: a FeGaSmalloy that is represented by Expression (1),Fe_((100-x-y))Ga_(x)Sm_(y)  (1) (in Expression (1), x and y arerespectively a content rate (at. %) of Ga and a content rate (at. %) ofSm, and satisfy that y≤0.35x−4.2, y≤−x+20.1, and y≥0.1x+2.1).
 2. Themagnetorstrictive material of claim 1, wherein in Expression (1), x andy satisfy that 17≤x≤18 and 0.7≤y≤1.4.
 3. The magnetostrictive materialof claim 2, wherein an orientation difference of <100> orientation ofthe FeGaSm alloy is in a range of 0° or greater and 10° or less, withrespect to a maximum strain direction of the magnetostrictive material.4. A magnetostriction type device comprising: the magnetostrictivematerial of claim 3, wherein a maximum strain direction of themagnetostrictive material is configured to form an inclination angle of0° or greater and 10° or less, with respect to a predetermined directionof a dimensional change of the magnetostriction type device.
 5. Amagnetostriction type device comprising: the magnetostrictive materialof claim 2, wherein a maximum strain direction of the magnetostrictivematerial is configured to form an inclination angle of 0° or greater and10° or less, with respect to a predetermined direction of a dimensionalchange of the magnetostriction type device.
 6. A magnetostriction typedevice comprising: the magnetostrictive material of claim 1, wherein amaximum strain direction of the magnetostrictive material is configuredto form an inclination angle of 0° or greater and 10° or less, withrespect to a predetermined direction of a dimensional change of themagnetostriction type device.
 7. The magnetostrictive material of claim1, wherein an orientation difference of <100> orientation of the FeGaSmalloy is in a range of 0° or greater and 10° or less, with respect to amaximum strain direction of the magnetostrictive material.